This application claims the priority of German application 198 17 911.1, filed Apr. 22, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a step bearing having a housing comprising a take-up in the form of a lubricating grease reservoir for taking up a freely rotatable supporting ball, and a front end supporting surface of a shaft of an open-end spinning rotor. The shaft is loaded with an axial force and the supporting surface is disposable on the supporting ball. The step bearing housing also accommodates thrust bearing supporting the supporting ball.
Lubricating the supporting ball with grease instead of oil brings with it the essential advantage that the machine does not become covered in oil and thus remains cleaner. The grease lubrication, however, must be designed in a very particular way, so that an equally good operational efficiency is achieved as with an oil supporting ball.
A step bearing housing comprising a take-up space in the form of a lubricating grease reservoir for a supporting ball is known from U.S. Pat. No. 4,618,273. The lubricating grease reservoir is relatively large here, so that it can be assumed that in the case of an increase in heat, a flowing motion arises, even if it is a slow one, by means of which the lubrication of the supporting ball is permitted. A collector for used lubricating grease is arranged at the take-up area for lubricating grease. When the supply of lubricating grease is used up, a new supply of lubricating grease can be applied to the take-up with the aid of a correspondingly formed lubricating grease press.
It has been shown that, up to the present, dependent on the amount of used lubricating grease, sometimes no grease reaches the critical place between the supporting surface of the shaft and the supporting ball. When the grease in direct proximity to the supporting ball is used up, when it contains hardly any more oil, it can happen that there is insufficient lubrication, namely principally in the case of relatively small lubricating grease reservoirs, in which there is not enough new, unused grease being pressed through. Also, used lubricating grease is not always removed efficiently enough.
It is an object of the present invention to avoid these disadvantages and to design a step bearing housing, in which lubricating grease can be applied at the right time, and without a complicated procedure, to the critical places of the supporting ball, while at the same time removing the used lubricating grease from these same places.
This object has been achieved according to the present invention in that a lubricant distributor, operated from the outside, is arranged at the take-up and is movable relative thereto.
When means are provided to set the lubricating grease reservoir in motion after a certain running time, then a small lubricating grease reservoir is sufficient which is small and handy and can be applied to the machine in exchange without any great disassembly taking place. This lubricant distributor can be operated from the outside at certain maintenance intervals by an operator, without the step bearing housing being disassembled, by means of a simple handle or a suitable tool. Thus the lubricating grease is "stirred", whereby used lubricating grease is removed from the old place and new lubricating grease is applied again to the supporting ball.
The present invention is based on the knowledge that after even a long running time of the step bearing, only a very small percent of the grease is actually used. Most of the grease filling is, for lubricating purposes, new and completely usable. When the grease is stirred from time to time, the lubricating of the supporting ball is ensured.
In the simplest embodiment of the present invention, the lubricant distributor can be designed as an adjustable closing piece, thus reducing the size of the take-up. Such a closing piece, which can, for example, form the closing lid of the take-up, can be screwed lower into the take-up by means of a screw thread for the purpose of subsequent lubrication, or it can be pressed in from time to time further into the take-up by means of a clip connection or the like. When re-adjusting, new grease is pressed onto the critical place and the used grease is pressed out.
The closing piece can, for example, take the form of a locking ball. According to the number of notches provided, the grease in the lubricating grease reservoir can be made to circulate several times.
It is practical for the purposes of the present invention when the closing piece is provided with a hollow which enlarges the take-up. The closing piece has then, for example, the shape of a hat, whose inner hollow space is a component of the take-up. By pressing the closing piece down, the grease located in close proximity to the supporting ball is displaced by means of pressing out. The excess grease enters an outer chamber, where it does no damage.
The described methods have the advantage in that the operating personnel do not have to work with a grease press, where, in the case of carelessness, it can happen that too much grease is applied and grease thus gets into parts where it is not required.
In an advantageous embodiment of the present invention, the lubricating grease reservoir is designed as an insert turnable in relation to the take-up. When, after a pre-determined running time, the grease supply to the supporting ball is to be secured again, the operating personnel are instructed to turn the insert by a pre-determined amount relative to the step bearing housing, or alternatively in the case of a stationarily arranged insert, to turn the step bearing housing relative thereto. This results in a kind of twirling effect. This can be increased in that the insert has a wing-like form, whereby the wings extend somewhat slanted, so that a screw effect arises. If the insert is turned too much, no damage is done, as the amount of grease in the inside of the lubricating grease reservoir does not change. In addition, no grease is released outside which might make keeping the machine clean difficult. The purpose of the insert is to make full use of the lubricating grease located in the take-up. This permits a reliable lubrication without grease re-fill occurring too quickly.
For the purpose of the present invention, the insert, or the step bearing housing movable relative thereto, is provided with working surfaces for a tool.
The insert can be applied in different ways in the step bearing housing. In one embodiment according to the present invention, it is possible to apply the insert to the step bearing housing from the side of the thrust bearing. In another embodiment according to the present invention, the insert is applied to the step bearing housing from the side of the shaft of the open-end spinning rotor.
The insert can be so designed that it borders the take-up with a radial web. An opening for the shaft can be provided in the web, whereby a non-contact seal is provided. When the end of the shaft is accordingly graduated, a labyrinth seal can thus be formed in this way.
In a particularly advantageous embodiment of the present invention, it is provided that the insert comprises finger-like turnable wings surrounding the supporting ball at a distance, the axis of which turnable wings,lies coaxial to the shaft. Because of the turning of the turnable wings, the grease is forced to escape, and is pressed unavoidably towards the critical point of the supporting ball. By means of the small distance to the supporting ball, the turnable wings can at the same time form a securing device so that when the shaft of the open-end spinning rotor is pulled out, the supporting ball essentially holds its operational position and returns to its operational position after the shaft is guided in again.
It is particularly favorable when stationarily arranged stopping ribs are arranged at the turnable wings. These ribs can, for example, project radially inwardly from a hollow cylindrical peripheral wall of the take-up, and the turnable wings can be movable between the stopping ribs. When the turnable ribs push against a stopping rib, this is a signal for the operator that the turnable wings must be turned in the other direction for the next lubrication. The turnable wing is always turned in that direction which is currently possible.
The stopping ribs can also surround the supporting ball at a short distance thereto, so that they also function as a support when the shaft of the open-end spinning rotor is removed.
A collector for lubricating grease can be arranged at the takeup. Thus used grease, which has to a great extent become liquid, flows from the take-up to the collector. Thus, when the grease is "stirred" by means of the lubricant distributor, the lubricating grease always reaches only those parts where it is either needed or where it does no damage. Additionally it can be provided that the take-up is separated from the collector by the insert itself.
In a further, particularly advantageous embodiment of the present invention, the step bearing housing takes the form of a cartridge, which forms, together with the supporting ball, an exchangeable spare part. Thus the possibility is retained, when the lubricating grease is finally used up, to exchange the cartridge for a cartridge with new lubricating grease. This exchange takes place infrequently due to the activity of the lubricant distributor according to the present invention. However, when the exchange must eventually take place, it is very simple to execute. The work involved and subsequently the costs for relubricating a step bearing are considerably reduced. In place of the removed cartridge, a new cartridge with the necessary supply of lubricating grease and a new supporting ball is applied. By activating the lubricant distributor between two cartridge exchange periods, the time intervals for exchanging a cartridge are significantly reduced.